The invention relates to a method for controlling an electro-surgical high-frequency (“HF”) generator and an electro-surgical device.
Modern surgery frequently makes use of electro-surgical devices including a high-frequency generator for generating a high-frequency alternating current. This high-frequency alternating current is then used to cut or coagulate biological tissue or treat it in some other way.
The fundamental frequency of the HF generator is usually between 300 kHz and 4 MHz. Depending upon the application, this high-frequency is modulated in different ways with respect to its amplitudes. Usually, pulse duration modulation is performed in order to determine the power applied. Here, the ratio of burst-type signal segments to succeeding pauses is set. The clock frequency or modulation is usually performed with frequencies of between 1 kHz and 50 kHz.
In addition, further modulation (switching the output signal on and off) is performed with very low frequencies between 1 Hz and 10 Hz to achieve a power intensity which enables the operator to follow the progress of the treatment.
Finally, to avoid leakage currents or losses from the generators during idling with no load, very low-frequency pulses (e.g., sine beats of the fundamental frequency) are used.
In addition to electro-surgical devices, a plurality of other electrical or electronic devices is used in the operating theatre. These include, for example, patient monitoring devices (for example EEG devices) or video devices. A typical example of a video device essential for an operation is in operations performed using endoscopy. In this case, the video chip is located in the immediate vicinity of the location at which an electro-surgical instrument is used to apply the above-described high-frequency alternating current to tissue.
In all the above cases, there is frequently interference with the electronic device, which could even result in the failure of the patient monitor used meaning that, after a certain time, it is not possible to monitor the vital parameters of the patient. The same applies to the video picture. In all cases, problems of this kind can have fatal consequences for the patient.